Throckmorton isn’t as well known as his elder brothers like Sir Nicholas and Sir Robert. John most likely started his career at court inside the household of Queen Katherine. In the years to come, he definitely had his cousin, Queen Katherine, to thank for his advancement at court. However, when she died in 1548, the advancement wasn’t favored as much and John had to rely on others like the Duke of Northumberland who took over after Edward VI sent his uncle [and Lord Protector] to the scaffold. Among the leading men, Throckmorton had several friends and family links; Queen Katherine’s brother, William, who was now Marquess of Northampton, and the Earl of Pembroke who had married the queen’s sister, Anne.
When the little curbuffle with Lady Jane Grey came to pass — loyalties changed. After Sir William Cecil refused to write up the proclamation of Lady Jane becoming queen, the task was given to Throckmorton. Like Cecil, he refused to have anything to do with it. Throckmorton would go on to back the Lady Mary [eldest daughter of King Henry VIII by his first wife, Katherine of Aragon] at Framlingham. Those who remained with Lady Jane [including one of his brothers and the Marquess of Northampton], were met with harsh penalties and punishment for their treason against Mary. His cousin, John [II], was eventually executed under Mary’s command for his role in the Dudley conspriracy.
During the five Marian parliaments, Throckmorton would be present for four. His first appearance, with his brother Nicholas, was most likely due to their cousin-in-law, William Herbert, Earl of Pembroke [husband to the late Anne Parr, sister of Queen Catherine and the Marquess of Northampton]. As a Catholic, Throckmorton suffered somewhat under the reign of Mary’s sister, Elizabeth. Four years after his death, his heir would be executed for his role in a revolt against the Protestant queen Elizabeth.
Throckmorton married to Margaret Puttenham, daughter of Robert of Sherfield-upon-Loddon. They had at least four sons and two daughters. His son, Francis, would be involved in the great Throckmorton Plot of 1584 which would have replaced Queen Elizabeth with Mary, Queen of Scots [a senior legitimate descendant of the Tudor family by King Henry VIII’s elder sister, Princess Margaret]. Francis is featured in the film Elizabeth: The Golden Age.
By both parents, John was cousin to Queen Katherine Parr. However, his mother was the queen’s paternal aunt as her father and Katherine shared the same mother. Parr’s father was the result of his mother’s first marriage to Sir William Parr, Lord of Kendal, while Katherine was the result of their mother’s second marriage to the Lancastrian Sir Nicholas Vaux [later Baron Vaux of Harrowden]. By Katherine Parr’s mother, Maud Green, Katherine was a second cousin, once removed of Sir George Throckmorton as they shared Sir John Throckmorton (born circa 1380) and Eleanor de la Spiney (born circa 1385) as common ancestors.